Too-high levees worsen Mississippi flooding in nearby towns, according to new computer model - Entrepreneur Generations

If the calamitous Mississippi River flood of 1993 happened today, some towns would fare far better while others fare worse, according to a new computer model by the Army Corps of Engineers that simulates how floods affect the Upper Mississippi. That's because some communities have raised their own levees without obtaining the proper permits, which shunts flood waters to neighboring towns and their farms. Residents of Pike County, Missouri, say the worsening floods in their towns are because their neighbors across the river in the Sny Island Levee Drainage District in Illinois have raised their levees too high.

"It’s for this very reason that the Corps regulates levee heights. Levees are designed to prevent rivers from overflowing, but they create a zero-sum game where raising levees in one area can push extra flood risk onto others," according to a ProPublica story. The story is a collaboration between Lisa Song and Al Shaw of ProPublica, Patrick Michaels of Reveal from The Center for Investigative Reporting, and Alex Heeb of The Telegraph in Alton, Ill.

Communities fight floods by putting up sandbags, but are expected to remove them afterward. But not all do, and over time the sandbags add up to too-high levees. The Corps is stretched too thin to monitor such levees, so they get left up.

Early tests show that if another big flood happens, "communities with higher levees — found in a handful of levee districts on both the Illinois and Missouri sides of the river — would be far better protected, and those without them would fare far worse," ProPublica reports. "On the Illinois side, the land behind the Sny’s higher levees would be much drier, with some areas saved from more than 16 feet of flooding. The Missouri side would weather floodwaters up to 1.7 feet higher than it experienced in 1993.

The first publicly available results of the simulation say that the worst impact of flooding would be in Pike County, the Union Township area, and the city of Hannibal, all in Missouri, ProPublica reports.

from The Rural Blog https://ift.tt/2Q7Cmkf Too-high levees worsen Mississippi flooding in nearby towns, according to new computer model - Entrepreneur Generations

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